With no load, (like when he steps on the clutch) if the throttle is not closing the rpms will rise. My guess is that it rises to a point and stops. It is a quick thing to check and clean before throwing money at it.
Green 2000 SVT #1166
mods-K&N and Custom heat shield, optimized y pipe, Magnaflow center resonator, DMDhttp://www.geocities.com/savinoss/Cars.html
-Wifes car 99 Mystique V6 5 spd